Image capture device and operation method thereof

ABSTRACT

An image capture device includes a light source, an image capture circuit, and a processor. The light source is used for generating emitting light. The image capture circuit is used for capturing an image corresponding to the emitting light. The processor is coupled to the light source and the image capture circuit for optionally adjusting the intensity of the emitting light of the light source according to luminance corresponding to the image and a target value.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image capture device and anoperation method thereof, and particularly to an image capture deviceand an operation method thereof that can ensure that a light source ofthe image capture device does not damage eyes of a user within a maximumoperation distance of emitting light generated by the light source.

2. Description of the Prior Art

Although structure light can increase quality of a depth map, thestructure light is usually emitted by stronger power to increase anoperation distance of the structure light, wherein the prior artspecifies that luminance of the structure light corresponding to amaximum operation distance of the structure light cannot damage eyes ofa user. Although the luminance of the structure light corresponding tothe maximum operation distance does not damage the eyes of the user, theeyes of the user may still be damaged within the maximum operationdistance under the same power which makes the luminance of the structurelight corresponding to the maximum operation distance not damage theeyes of the user. Because an interactive audio and video device whichcan interact with the user becomes gradually popular, how to make theeyes of the user not be damaged within a maximum operation distance ofthe interactive audio and video device becomes an important issue.

SUMMARY OF THE INVENTION

An embodiment of the present invention provides an image capture device.The image capture device includes a light source, an image capturecircuit, and a processor. The light source is used for generatingemitting light. The image capture circuit is used for capturing an imagecorresponding to the emitting light. The processor is coupled to theimage capture circuit and the light source for optionally adjustingintensity of the emitting light of the light source according toluminance corresponding to the image and a target value.

Another embodiment of the present invention provides an operation methodof an image capture device, wherein the image capture device includes alight source, an image capture circuit, and a processor. The operationmethod includes the light source generating emitting light; the imagecapture circuit capturing an image corresponding to the emitting light;and the processor optionally adjusting intensity of the emitting lightof the light source according to luminance corresponding to the imageand a target value.

The present invention provides an image capture device and an operationmethod thereof. The image capture device and the operation methodutilize a processor optionally adjust intensity of emitting light of alight source of the image capture device according to differentluminance values of an image corresponding to the emitting light of thelight source and a target value. Therefore, compared to the prior art,the present invention can ensure that the light source of the imagecapture device does not damage eyes of a user within a maximum operationdistance of the emitting light generated by the light source.

These and other objectives of the present invention will no doubt becomeobvious to those of ordinary skill in the art after reading thefollowing detailed description of the preferred embodiment that isillustrated in the various figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an image capture device according to afirst embodiment of the present invention.

FIG. 2 is a diagram illustrating an image corresponding to the emittinglight of the light source.

FIG. 3 is a diagram illustrating an image capture range of the imagecapture circuit being almost equal to an emitting angle of the lightsource.

FIG. 4 is a diagram illustrating a luminance distribution mapcorresponding to the image.

FIG. 5 is a top view corresponding to the luminance distribution mapshown in FIG. 4.

FIG. 6 is a diagram illustrating a luminance value less than the targetvalue.

FIG. 7 is a diagram illustrating a luminance histogram corresponding tothe image.

FIG. 8 is a flowchart illustrating an operation method of an imagecapture device according to a second embodiment of the presentinvention.

FIG. 9 is a flowchart illustrating an operation method of an imagecapture device according to a third embodiment of the present invention.

FIG. 10 is a flowchart illustrating an operation method of an imagecapture device according to a fourth embodiment of the presentinvention.

DETAILED DESCRIPTION

Please refer to FIG. 1. FIG. 1 is a diagram illustrating an imagecapture device 100 according to a first embodiment of the presentinvention. As shown in FIG. 1, the image capture device 100 includes alight source 102, an image capture circuit 104, and a processor 106,wherein the processor 106 is coupled to the image capture circuit 104and the light source 102, and the image capture device 100 is applied toan interactive audio and video device. The light source 102 is used forgenerating emitting light, wherein the light source 102 can be a laserlight source, a light emitting diode light source, or an infrared raylight source. The image capture circuit 104 is used for capturing animage IM (shown in FIG. 2) corresponding to the emitting light, whereinan image capture range ICR of the image capture circuit 104 is almostequal to an emitting angle EA (shown in FIG. 3) of the light source 102,and the image IM includes a user 108, a mural 110, and a background.After the image capture circuit 104 captures the image IM, the processor106 can generate a luminance distribution map LDM (shown in FIG. 4)corresponding to the image IM according to the image IM, wherein asshown in FIG. 4, a belt buckle 1082 of the user 108 has a luminancevalue L1, a face of the user 108 has a luminance value L2, and the mural110 has a luminance value L3. In addition, the luminance value L1 of thebelt buckle 1082 and the luminance value L2 of the face of the user 108are greater than a target value TH, the luminance value L3 of the mural110 is less than the target value TH, and the luminance value L1 isgreater than the luminance value L2. After the processor 106 generatesthe luminance distribution map LDM corresponding to the image IM, theprocessor 106 can optionally adjust intensity of the emitting light ofthe light source 102 to make an adjusted maximum luminance value beclose to the target value TH according to a percentage of the image IMoccupied by an area corresponding to the maximum luminance value of atleast one luminance value within the luminance distribution map LDMgreater than the target value TH, wherein because a purpose of thepresent invention is used for preventing eyes of the user 108 from beingdamaged, the target value TH is set according to a reflectioncoefficient of a human skin of the user 108 corresponding to theemitting light of the light source 102. Therefore, as shown in FIG. 5(wherein FIG. 5 is a top view corresponding to the luminancedistribution map LDM shown in FIG. 4), because the luminance value L1 isgreater than the luminance value L2, and the luminance value L1 and theluminance value L2 are greater than the target value TH, the processor106 can first determine whether a percentage of the image IM occupied byan area A corresponding to the luminance value L1 is less than apredetermined percentage (wherein the predetermined percentage is setaccording to an area of the face of the user 108, and the area A isapproximately equal to an area of the belt buckle 1082 of the user 108).However, in another embodiment of the present invention, the processor106 utilizes a face recognition method provided by the prior art torecognize face (s) within the image IM. Because the percentage of theimage IM occupied by the area A corresponding to the luminance value L1is less than the predetermined percentage, the processor 106 does notreduce the intensity of the emitting light of the light source 102 tomake the luminance value L1 be close to the target value TH. However,after the processor 106 does not reduce the intensity of the emittinglight of the light source 102 to make the luminance value L1 be close tothe target value TH, then the processor 106 determines whether apercentage of the image IM occupied by an area B corresponding to theluminance value L2 is less than the predetermined percentage. Becausethe percentage of the image IM occupied by the area B corresponding tothe luminance value L2 is greater than the predetermined percentage(wherein the area B is approximately equal to the area of the face ofthe user 108) , the processor 106 can reduce the intensity of theemitting light of the light source 102 to make the adjusted luminancevalue L2 be close to the target value TH, wherein the processor 106utilizes a digital dimming method to reduce the intensity of theemitting light of the light source 102 to make the adjusted luminancevalue L2 be close to the target value TH. For example, the processor 106reduces a duty cycle of a pulse width modulation (PWM) signal inputtedto the light source 102 to make the adjusted luminance value L2 be closeto the target value TH. But, in another embodiment of the presentinvention, the processor 106 utilizes an analog dimming method to reducethe intensity of the emitting light of the light source 102 to make theadjusted luminance value L2 be close to the target value TH. Forexample, the processor 106 utilizes a programmable variable resistor toreduce a current or a voltage inputted to the light source 102 (or tosimultaneously adjust the current and the voltage inputted to the lightsource 102) to make the adjusted luminance value L2 be close to thetarget value TH. In addition, in another embodiment of the presentinvention, when the light source 102 is a programmable dimming lightsource (that is, the light source 102 is a light source which can bedimmed by partition) , the processor 106 can reduce intensity of a partof the emitting light of the light source 102 only corresponding to theluminance value L2 to make the adjusted luminance value L2 be close tothe target value TH. In addition, in another embodiment of the presentinvention, when the light source 102 is a programmable dimming lightsource, the processor 106 can reduce intensity of a part of the emittinglight of the light source 102 only corresponding to each luminance valuegenerated by the light source 102 greater than the target value TH(wherein a percentage of the image IM occupied by an area correspondingto the each luminance value is greater than the predeterminedpercentage) respectively to make the each adjusted luminance value beclose to the target value TH. In addition, because the processor 106 canalso process luminance values of clothes and pants of the user 108included in the image IM according to the above mentioned principles, sofurther description thereof is omitted for simplicity. In addition, inanother embodiment of the present invention, because the luminance valueL2 is less than the target value TH (shown in FIG. 6) , the processor106 can increase the intensity of the emitting light of the light source102 to make the adjusted luminance value L2 be close to the target valueTH.

In addition, if three luminance values or more than three luminancevalues within the luminance distribution map LDM are greater than thetarget value TH, the processor 106 can also determine how to adjust theintensity of the emitting light of the light source 102 according to theabove mentioned principles.

In addition, in another embodiment of the present invention, theprocessor 106 can optionally adjust the intensity of the emitting lightof the light source 102 according to average luminance corresponding tothe image IM to make the adjusted average luminance corresponding to theimage IM be close to the target value TH. For example, when the averageluminance corresponding to the image IM is greater than the target valueTH, the processor 106 can reduce the intensity of the emitting light ofthe light source 102 to make the adjusted average luminancecorresponding to the image IM be close to the target value TH; and whenthe average luminance corresponding to the image IM is less than thetarget value TH, the processor 106 can increase the intensity of theemitting light of the light source 102 to make the adjusted averageluminance corresponding to the image IM be close to the target value TH.

In addition, in another embodiment of the present invention, theprocessor 106 can adjust the intensity of the emitting light of thelight source 102 according to a median or a quartile of a luminancehistogram corresponding to a plurality of pixels of the image IM to makea new median or a new quartile corresponding to the image IM be close tothe target value TH. For example, the processor 106 can utilize a valuewithin 0-255 (corresponding to 8 bits) to represent luminance of eachpixel of the image IM to generate a luminance histogram LH (shown inFIG. 7, wherein FIG. 7 is used for describing the present invention,that is, the present invention is not limited to FIG. 7) correspondingto 1000 pixels of the image IM. As shown in FIG. 7, because 100 pixelsof the image IM have a luminance value 75, 100 pixels of the image IMhave a luminance value 100, 200 pixels of the image IM have a luminancevalue 120, 300 pixels of the image IM have a luminance value 150, 200pixels of the image IM have a luminance value 190, and 100 pixels of theimage IM have a luminance value 210, a median of the luminance histogramLH corresponding to the 1000 pixels of the image IM is equal to 150.Thus, the processor 106 can increase (when the median (150) is less thanthe target value TH) or decrease (when the median (150) is greater thanthe target value TH) the intensity of the emitting light of the lightsource 102 according to the median (150) of the luminance histogram LHcorresponding to the 1000 pixels of the image IM and the target value THto make a new median of an adjusted luminance histogram corresponding tothe 1000 pixels of the image IM be close to the target value TH. Inaddition, the present invention is not limited to utilizing a valuewithin 0-255 to represent luminance of each pixel of the image IM. Thatis to say, the present invention can also utilize a value correspondingto other bits (e.g. 16 bits) to represent luminance of each pixel of theimage IM. In addition, any configuration in which the processor 106adjusts the intensity of the emitting light of the light source 102according to the luminance corresponding to the image IM and the targetvalue TH falls within the scope of the present invention.

Please refer to FIGS. 1-6, 8. FIG. 8 is a flowchart illustrating anoperation method of an image capture device according to a secondembodiment of the present invention. The operation method in FIG. 8 isillustrated using the image capture device 100 in FIG. 1. Detailed stepsare as follows:

Step 800: Start.

Step 802: The light source 102 generates the emitting light.

Step 804: The image capture circuit 104 captures the image IMcorresponding to the emitting light.

Step 806: The processor 106 generates the luminance distribution map LDMcorresponding to the image IM according to the image IM.

Step 808: If at least one luminance value of the luminance distributionmap LDM is greater than the target value TH; if yes, go to Step 810; ifno, go to Step 812.

Step 810: The processor 106 optionally adjusts the intensity of theemitting light of the light source 102 according to the at least oneluminance value.

Step 812: End.

In Step 806, after the image capture circuit 104 captures the image IM,the processor 106 can generate the luminance distribution map LDM (shownin FIG. 4) corresponding to the image IM according to the image IM,wherein as shown in FIG. 4, the luminance value L1 of the belt buckle1082 and the luminance value L2 of the face of the user 108 are greaterthan the target value TH, the luminance value L3 of the mural 110 isless than the target value TH, and the luminance value L1 is greaterthan the luminance value L2. In addition, because the purpose of thepresent invention is used for preventing the eyes of the user 108 frombeing damaged, the target value TH is set according to the reflectioncoefficient of the human skin of the user 108 corresponding to theemitting light of the light source 102. Therefore, in Step 810, as shownin FIG. 5, because the luminance value L1 is greater than the luminancevalue L2, and the luminance value L1 and the luminance value L2 aregreater than the target value TH, the processor 106 can first determinewhether the percentage of the image IM occupied by the area Acorresponding to the luminance value L1 is less than the predeterminedpercentage. However, in another embodiment of the present invention, theprocessor 106 utilizes the face recognition method provided by the priorart to recognize face (s) within the image IM. Because the percentage ofthe image IM occupied by the area A corresponding to the luminance valueL1 is less than the predetermined percentage, the processor 106 does notreduce the intensity of the emitting light of the light source 102 tomake the luminance value L1 be close to the target value TH. However,after the processor 106 does not reduce the intensity of the emittinglight of the light source 102 to make the luminance value L1 be close tothe target value TH, then the processor 106 determines whether thepercentage of the image IM occupied by the area B corresponding to theluminance value L2 is less than the predetermined percentage. Becausethe percentage of the image IM occupied by the area B corresponding tothe luminance value L2 is greater than the predetermined percentage, theprocessor 106 can reduce the intensity of the emitting light of thelight source 102 to make the adjusted luminance value L2 be close to thetarget value TH. In addition, the processor 106 can also process theluminance values of the clothes and the pants of the user 108 includedin the image IM according to the above mentioned principles, so furtherdescription thereof is omitted for simplicity. In addition, in anotherembodiment of the present invention, because the luminance value L2 isless than the target value TH (shown in FIG. 6), the processor 106 canincrease the intensity of the emitting light of the light source 102 tomake the adjusted luminance value L2 be close to the target value TH.

In addition, if three luminance values or more than three luminancevalues within the luminance distribution map LDM are greater than thetarget value TH, the processor 106 can also determine how to adjust theintensity of the emitting light of the light source 102 according to theabove mentioned principles.

Please refer to FIGS. 1, 9. FIG. 9 is a flowchart illustrating anoperation method of an image capture device according to a thirdembodiment of the present invention. The operation method in FIG. 9 isillustrated using the image capture device 100 in FIG. 1. Detailed stepsare as follows:

Step 900: Start.

Step 902: The light source 102 generates the emitting light.

Step 904: The image capture circuit 104 captures the image IMcorresponding to the emitting light.

Step 906: The processor 106 generates the average luminancecorresponding to the image IM according to the image IM.

Step 908: The processor 106 optionally adjusts the intensity of theemitting light of the light source 102 according to the averageluminance corresponding to the image IM and the target value TH to makethe adjusted average luminance be close to the target value TH.

Step 910: End.

Differences between the embodiment in FIG. 9 and the embodiment in FIG.8 are that in Step 906 and Step 908, the processor 106 first generatesthe average luminance corresponding to the image IM according to theimage IM; and when the average luminance corresponding to the image IMis greater than the target value TH, the processor 106 reduces theintensity of the emitting light of the light source 102 to make theadjusted average luminance corresponding to the image IM be close to thetarget value TH, and when the average luminance corresponding to theimage IM is less than the target value TH, the processor 106 increasesthe intensity of the emitting light of the light source 102 to make theadjusted average luminance corresponding to the image IM be close to thetarget value TH.

Please refer to FIGS. 1, 7, 10. FIG. 10 is a flowchart illustrating anoperation method of an image capture device according to a fourthembodiment of the present invention. The operation method in FIG. 10 isillustrated using the image capture device 100 in FIG. 1. Detailed stepsare as follows:

Step 1000: Start.

Step 1002: The light source 102 generates the emitting light.

Step 1004: The image capture circuit 104 captures the image IMcorresponding to the emitting light.

Step 1006: The processor 106 generates the luminance histogram LHcorresponding to the plurality of pixels of the image IM according tothe image IM.

Step 1008: The processor 106 optionally adjusts the intensity of theemitting light of the light source 102 according to the median of theluminance histogram LH and the target value TH to make a new mediancorresponding to the image IM be close to the target value TH.

Step 1010: End.

Differences between the embodiment in FIG. 10 and the embodiment in FIG.8 are that in Step 1006, the processor 106 can first utilize a valuewithin 0-255 (corresponding to 8 bits) to represent luminance of eachpixel of the image IM to generate the luminance histogram LH (shown inFIG. 7) corresponding to the 1000 pixels of the image IM; and in Step1008, as shown in FIG. 7, because 100 pixels of the image IM have theluminance value 75, 100 pixels of the image IM have the luminance value100, 200 pixels of the image IM have the luminance value 120, 300 pixelsof the image IM have the luminance value 150, 200 pixels of the image IMhave the luminance value 190, and 100 pixels of the image IM have theluminance value 210, the median of the luminance histogram LHcorresponding to the 1000 pixels of the image IM is equal to 150. Thus,the processor 106 can increase (when the median (150) is less than thetarget value TH) or decrease (when the median (150) is greater than thetarget value TH) the intensity of the emitting light of the light source102 according to the median (150) of the luminance histogram LHcorresponding to the 1000 pixels of the image IM and the target value THto make a new median of an adjusted luminance histogram corresponding tothe 1000 pixels of the image IM be close to the target value TH. Inaddition, the present invention is not limited to utilizing a valuewithin 0-255 to represent luminance of each pixel of the image IM. Thatis to say, the present invention can also utilize a value correspondingto other bits (e.g. 16 bits) to represent luminance of each pixel of theimage IM. In addition, in another embodiment of the present invention,the processor 106 can determine how to adjust the intensity of theemitting light of the light source 102 according to a quartile ofluminance histogram LH and the target value TH to make a new quartilecorresponding to the image IM be close to the target value TH.

In addition, any configuration in which the processor 106 adjusts theintensity of the emitting light of the light source 102 according to theluminance corresponding to the image IM and the target value TH fallswithin the scope of the present invention.

To sum up, the image capture device and the operation method thereofutilize the processor to optionally adjust the intensity of the emittinglight of the light source according to different luminance values of animage corresponding to the emitting light of the light source and thetarget value. Therefore, compared to the prior art, the presentinvention can ensure that the light source of the image capture devicedoes not damage the eyes of the user within a maximum operation distanceof the emitting light generated by the light source.

Those skilled in the art will readily observe that numerousmodifications and alterations of the device and method may be made whileretaining the teachings of the invention. Accordingly, the abovedisclosure should be construed as limited only by the metes and boundsof the appended claims.

What is claimed is:
 1. An image capture device, comprising: a lightsource generating emitting light; an image capture circuit capturing animage corresponding to the emitting light; and a processor coupled tothe image capture circuit and the light source for optionally adjustingintensity of the emitting light of the light source according toluminance corresponding to the image and a target value.
 2. The imagecapture device of claim 1, wherein the processor generates a luminancedistribution map corresponding to the image according to the image, andoptionally adjusts the intensity of the emitting light of the lightsource according to at least one luminance value within the luminancedistribution map greater than the target value.
 3. The image capturedevice of claim 2, wherein the processor optionally adjusts theintensity of the emitting light of the light source according to apercentage of the image occupied by an area corresponding to a maximumluminance value of the at least one luminance value to make the adjustedmaximum luminance value be close to the target value.
 4. The imagecapture device of claim 3, wherein the processor utilizes a digitaldimming method or an analog dimming method to adjust the intensity ofthe emitting light to make the adjusted maximum luminance value be closeto the target value.
 5. The image capture device of claim 3, wherein theprocessor adjusts intensity of emitting light generated by the lightsource only corresponding to the maximum luminance value to make theadjusted maximum luminance value be close to the target value.
 6. Theimage capture device of claim 3, wherein when the processor determinesnot to adjust the intensity of the emitting light to make the maximumluminance value be close to the target value, the processor furtheroptionally adjusts the intensity of the emitting light of the lightsource according to a percentage of the image occupied by an areacorresponding to a second greatest luminance value of the at least oneluminance value to make the adjusted second greatest luminance value beclose to the target value.
 7. The image capture device of claim 6,wherein when the processor determines not to adjust the intensity of theemitting light to make the second greatest luminance value be close tothe target value, the processor further optionally adjusts the intensityof the emitting light of the light source according to a percentage ofthe image occupied by an area corresponding to a third greatestluminance value of the at least one luminance value to make the adjustedthird greatest luminance value be close to the target value.
 8. Theimage capture device of claim 1, wherein the target value is setaccording to a reflection coefficient of a human skin corresponding tothe emitting light.
 9. The image capture device of claim 1, wherein theprocessor generates average luminance corresponding to the imageaccording to the image, and optionally adjusts the intensity of theemitting light of the light source according to the average luminanceand the target value.
 10. The image capture device of claim 1, whereinthe processor generates a luminance histogram corresponding to aplurality of pixels of the image according to the image, and optionallyadjusts the intensity of the emitting light of the light sourceaccording to a median of the luminance histogram and the target value,or a quartile of the luminance histogram and the target value.
 11. Anoperation method of an image capture device, wherein the image capturedevice comprises a light source, an image capture circuit, and aprocessor, the operation method comprising: the light source generatingemitting light; the image capture circuit capturing an imagecorresponding to the emitting light; and the processor optionallyadjusting intensity of the emitting light of the light source accordingto luminance corresponding to the image and a target value.
 12. Theoperation method of claim 11, wherein the processor optionally adjustingthe intensity of the emitting light of the light source according to theluminance corresponding to the image and the target value comprises: theprocessor generating a luminance distribution map corresponding to theimage according to the image; the processor optionally adjusting theintensity of the emitting light of the light source according to atleast one luminance value within the luminance distribution map greaterthan the target value.
 13. The operation method of claim 12, wherein theprocessor optionally adjusts the intensity of the emitting light of thelight source according to a percentage of the image occupied by an areacorresponding to a maximum luminance value of the at least one luminancevalue to make the adjusted maximum luminance value be close to thetarget value.
 14. The operation method of claim 13, wherein theprocessor utilizes a digital dimming method or an analog dimming methodto adjust the intensity of the emitting light to make the adjustedmaximum luminance value be close to the target value.
 15. The operationmethod of claim 13, wherein the processor adjusts intensity of emittinglight generated by the light source only corresponding to the maximumluminance value to make the adjusted maximum luminance value be close tothe target value.
 16. The operation method of claim 13, furthercomprising: the processor optionally adjusting the intensity of theemitting light of the light source according to a percentage of theimage occupied by an area corresponding to a second greatest luminancevalue of the at least one luminance value to make the adjusted secondgreatest luminance value be close to the target value when the processordetermines not to adjust the intensity of the emitting light to make themaximum luminance value be close to the target value.
 17. The operationmethod of claim 16, further comprising: the processor optionallyadjusting the intensity of the emitting light of the light sourceaccording to a percentage of the image occupied by an area correspondingto a third greatest luminance value of the at least one luminance valueto make the adjusted third greatest luminance value be close to thetarget value when the processor determines not to adjust the intensityof the emitting light to make the second greatest luminance value beclose to the target value.
 18. The operation method of claim 11, whereinthe target value is set according to a reflection coefficient of a humanskin corresponding to the emitting light.
 19. The operation method ofclaim 11, wherein the processor optionally adjusting the intensity ofthe emitting light of the light source according to the luminancecorresponding to the image and the target value comprises: the processorgenerating average luminance corresponding to the image according to theimage; and the processor optionally adjusting the intensity of theemitting light of the light source according to the average luminanceand the target value.
 20. The operation method of claim 11, wherein theprocessor optionally adjusting the intensity of the emitting light ofthe light source according to the luminance corresponding to the imageand the target value comprises: the processor generating a luminancehistogram corresponding to plurality of pixels of the image according tothe image; and the processor optionally adjusting the intensity of theemitting light of the light source according to a median of theluminance histogram and the target value, or a quartile of the luminancehistogram and the target value.